Rotary pumps



Feb 23, 1965 R. A. HILL ETAL 3,170,403

ROTARY PUMPS Original Filed Jan. 20, 1960 2 Sheets-Sheet 1 INVENTOR Pose-R7 A fl/LL HOWARD M 7bM/h5h0 BY QMV B TIORNEY Fb. 23; 1965 R. A. HILL ETAL 3,170,408

ROTARY PUMPS Original Filed Jan 20, 1960 2 Sheets-Sheet 2 INVENT OR Foster ,4. H144 WARD M. roMAs/w TTORNEY ROTARY PS Robert A. Hill and Howard M. Tomasko, Minneapoiis, Minn, assignors to Waterous Company, St. Paul, t 1., a corporation of Minnesota Original application Jan. 21?, 1969, Ser. No. 3,551, new Patent No. 3,106,166, dated Oct. 8, 1963. Dividedand this application July 16, 1962, Ser. No. 20?,839'

' 1 Claim. (Cl. 103-126) This inventionrelates to an improvement in rotary pumps, and deals particularly with a means of hydraulically balancing pump rotors.

In the operation of rotary pumps, the rotors do not at all times remain centered between the end plates of the pump. The friction between the ends of the rotors and the end plates causes the engaging parts to Wear, and to cause addedresistance to the rotation .of the rotors. Furthermore, when the rotors are centered, there is usually enough leakage between the rotors and the end plates to assist in lubricating the shaft seals. When the rotors move axially against one end plate, this leakage is reduced or eliminated, thuspreventing the liquid from reaching the seals in this end plate. Y i

It is an object of the present invention to provide a means of hydraulically balancing the rotors of rotary pumps to obviate the previous difficulties. This is -ac complished without appreciably .increasing'the cost of production, resulting in a better product at virtually no' additional cost. 1 t

A feature of this invention resides in providing a groove in each end plate leading from the discharge side or the pump to the seal chambers inthe end plates. With this be essentially equal to the pump discharge pressure. 5 At the same time, the clearance between the other end. of

the rotor and the adjacent end plate willincrease, allowing liquid to bleed readily from the: seal chamber to the suction side of the pump. .Thus the pressure in this charge pressure. This-variationjin pressure in the seal chambers creates an end thrust causing the rotor to return to a central position.

, secondseal chamber will be reduced below pump dis- This application isa divisional application of our pre- 7 viously filed patent for Pretimed Three-Lobed Rotary Pump, issued October 8, 1963, as Patent 3,106,166.

These and other objects and novel features of the present invention will bemore clearly and fully set forth in the following specification and claim.

In the drawings'forming a part of the specification;

FIGURE 1 is a vertical sectional view of a' rotary pump showing the general form of construction thereof. Q

FIGURE 2 is a cross-sectional view of the pump shown .in FIGURE 1, the position of the section being indicated The pump includes a housingltl having upper and lowerin position thereby.

The cylindrical skirt 34 of the valve 26 which slides outlet passage 21 in communication with the rotor chambers 13 and 14. The fluid being pumped enters the inlet 20, is carried between the rotor lobes and the arcuate walls 11 andf12. and are discharged through the discharge passage 21. Intermediate the ends of the rotors,

'a by-pass passage including passage'portions 22 and 23 extend from the discharge 21 to the inlet 20. A cylindrical passage 24 terminating in a valve seat 25, connects the passage portions 22 and 23. A pressure relief valve 26 is slidably supported in the cylindrical passage 24 and includes a beveled peripheral flange 27 designed to engage 7 against the valve seat 25.-

The relief valve 26 includes an axial boss 29. A plug 30 is threaded into an opening 31 in axial alignment with the valve 26'. The plug3tl; is provided withan axial and 37 which are properlylocated by'dowel pins 39 which extend through the end plates and into the housing 10. Bearing supporting plates 40 and 41 are secured in face contact with the end plates 36 and 37 and are also located relative .to the end plates and the pump housing by suitable means such asby the dowel pins 39. The bearing supporting plates 49 and .41 are apertured to accommodate a pair of sealed bearings 42 and 43, the apertures being indicated by the numerals 44 and 45. Seals 46 and 47 are supported in grooves 49 and 'Stlrespectively to seal the outer races of the bearings 42 and 43 relative to the walls of the apertures 44 and 45. The inner races of the bearings may be sealed relative to the shaft 17.

The bearing supporting plates 40 and 41 are also provided with a second pair of aligned apertures 51 and 52 which support sealed bearings 53 and 54 which support the shaft 19. The outer races of the bearings 53 and 54 are sealed relative to the apertures 51 and 52 by'seals 55 and 56.

The ends of the rotors 15 and 16 are provided with V axial sockets 57 and 59 respectively which include sealing units. As all of the seals are of identical form, the parts will be given similar identification numbers. Sealing rings 69 are slidably engaged in sockets 61 and 62' coarcuate portions 11 and 12 which form intersecting rotor 1 chambers 13 and 14designed to accommodate three;

lobed rotors 15 and 16 respectively. The rotors 15 and 16 are mounted upon supporting shafts 1'7 and 19 respectively. As is usual in pumps of this type, the lobes of the rotors engage in the hollow portions between the leakage between the two rotors.

The housing 16 includes an inlet passage z ti and an v axial with the shafts 17 and 19 in the end plates 36 andt 37. The rings 66 are sealed relative to the walls of the socket by 0, rings 63 located in the. externally grooved surface of the rings 69. A sealing ring64encircles the shaft 17 or 19 and is sealed relative thereto by 0 rings 65. The sealing ring 64 is urged intosealing relation with the ring 66 by means of a spring 66 interposed be tween the sealing ring 64 and the base of the socket 57 or 59. I A cover plate 67 overlies the bearing supporting plate 40 and is connected thereto by bolts 67" which extend through the cover plate, through the bearing supporting plate, the end plate, and into the pump housing 10. A

gear housing 69 including an end wall 70, a-peripheral wall'71 and an outwardly extending mounting flange 72 is connected to the other end of the pump housing by means of bolts 73 whicl1 extend through the flange 72, through the bearing Supporting plate 41, the end plate 37, "and-into the end of the housing 10. The end wall 70 is Patented Feb. 23, 1965 relation in the gears 77 and 79. The gears 77 provided with an opening 74 containing a seal 75 to accommodate the projecting end 76 of the drive shaft 17.

Gears 77 and 79 are pinned to the shaft 17 and 19 respectively by pairs of taper pins 80 and 81 extending diametrically to apertures 82 and 83 in axially spaced and 79 are provided with angularly spaced teeth. In FIGURE 2 of the drawings a groove 159 is shown in the end plate 36 forming an end wall of the pump. A similar groove is provided in the end plate 37. These grooves lead from thedischarge side of the pump to the seal chambers or sockets 57 and 59, subjecting these chambers substantially to discharge pressure. If the rotor moves axially until it rubs against the end plate the clearance at that end will be reduced to zero and the pressure in the seal chamberwill be substantially equal to discharge pressure. At the other end, however, the clearance between the rotor and the end plate will increase to a maximum, allowing liquid to bleed readily from the seal chamber to the suction side of the pump, reducing the pressure in the seal chamber to somewhat below discharge pressure.' This results in an end thrust tending to move the rotor to central position where it has equal clearance with each end plate.

In accordance with the patent statutes, we have described the principles of construction and operation of our improvement in rotary pumps, and while we have endeavored to set forth the best embodiment thereof, we desire to have it understood that changes may be made within the scope of the following claim without depart ing from the spirit of our invention. e i

We claim:

A rotary pump including a pair of lobed intermeshing rotors, rotor shafts in said rotors, a housing defining intersecting rotor chambers enclosing said rotors, said housing including a discharge outlet and a suction inlet on opposite sides of the intermeshing portions of said lobes, end plates closing the ends of said housing, means connected to said'end plates supporting said shafts in parallel relation, flat ends on said rotors substantially in sealing relation with said end plates, said rotors being axially slidable to vary the spacing between the rotor ends and said end plates, said rotors having axial sockets in the ends thereof, the inner surfaces of said end plates including sockets encircling said shafts, said inner surfaces also including grooves leading from said discharge outlet side of said housing to said sockets, all of said sockets having a diameter smaller than the roots of the lobes of said rotors, a sealing ring in each of said sockets in said end plates, and sealed relative thereto, a cooperable sealing ring in each axial socket in said rotor and engaging the first named sealing rings with a running fit, means urging saidcooperable sealing rings and first named sealing rings into engagement, said cooperable sealing rings being sealed relative to their shafts, whereby pressure in said sockets will assist in urging said sealing rings into engagement, and whereby axial movement of one rotor toward one end plate, increasing the distance between said one rotor and the other said end plate will permit fluid in thesocket in theother said end plate to flow to the suction inlet side of the housing and lower the fluid pressure in the socket in said other end plate until the rotor is forced to return to a position centralized between said end plates.

I References Cited in the file of this patent UNITED STATES PATENTS 

